Resistivity changes in silver due to plastic deformation

Abstract

The excess resistivity induced in high purity silver wires by torsion at shear strains of up to 250% at 77–293°k is shown to be a linear function of the square of the flow stress. A discontinuity in this relation at the transition from the linear, second stage of hardening to the third stage of work-hardening was not observed; but it is well defined by a sharp change of slope on curves relating the excess resistivity and the shear strain. The results show that the resistivity increases linearly with the density of dislocations, and suggest that a proportionality exists between the concentration of vacancies and the density of dislocations produced in the course of isothermal plastic deformation. The resistivity per centimetre of dislocation line in silver was estimated to be close to 2 × 10⁻¹⁹ ohm cm.